Well, I put the recipe into qBrew, and it gave honey's extract potential as 1.042, which would make the calculation correct. Other sources, including John Palmer's How To Brew and StrangeBrew give it as around 1.035, making hightest's correct.

Years ago, I attempted to use the beer brewing programs for mead and found them not suited to mead making. As I do not know the specifics of their calculation methodolgy, I can not say why this is so.

So rather than try to figure out why other programs do not work, I created my own, tailored to the needs of the mead maker. It is as accurate as your measurements, is used by many mead makers, and is the basis for mead calculators found on other mead websites...